D. J. Bernstein
Internet mail

8-bit text messages

An 8-bit text message means a sequence of lines. Each line is a string of zero or more 8-bit bytes.

A message is safe if none of its bytes are \012.

How are 8-bit messages stored under current operating systems?

Under DOS and Windows, a message is normally stored on disk as firstline\015\012secondline\015\012...\015\012lastline.

Under UNIX, a message is normally stored on disk as firstline\012secondline\012...\012lastline.

In practice, it is very common for the last line to be empty. A partial line means a nonempty last line. Beware that some text-processing utilities ignore partial lines.

Why are safe messages a useful concept?

The DOS and UNIX message encodings are reversible for safe messages. Any string of 8-bit bytes can be interpreted as a safe message in the UNIX encoding.